It's well known that a dog will notice its owner before strangers, but is it because of their smell, or because they recognize their owner's face? According to a new study, dogs do indeed recognize their owners' faces, even when the face is just an image on a screen. (Photo: ERersigni, CC BY 2.0)

If you've ever had a dog, or simply been around one, then you might be familiar with their ability to hold eye contact. For dog owners, this eye contact is present even when the owner isn't looking at the dog — the dog is always watching. Recent research has even shown that dogs don't just live in the moment, and instead, are able to remember events from the past. Therefore, it should come as no surprise that dogs remember their owners' faces, even when they're only looking at a photo, according to a study published in the journal Animal Cognition.

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Researchers at the University of Helsinki trained 23 pet dogs and eight kennel dogs to lay still while watching a series of images on a TV screen. The images included photos of both familiar and unfamiliar human faces as well as photos of other dogs, some of which had the same owner — all images alternated between being upright and inverted. "Dogs seemed to experience the task [as] rewarding, because they were very eager to participate," Dr. Outi Vainio, of the university, said in a press release.

Using eye-tracking technology, the researchers analyzed every dogs' eye movement to see which images produced the longest fixation. They first noticed that among all the images, the dogs fixated their gaze in the area around the eyes, which suggested that they were able to perceive faces in the images. Naturally, the dogs were most fixated conspecific faces — images of other dogs — just as they are more interested in meeting other dogs rather than humans when going out for a walk. After factoring that out, however, the researchers found that the dogs were fixated on both familiar human faces and dog faces for a longer amount of time.

"The results imply that face scanning in dogs is guided not only by the physical properties of images, but also by semantic factors," the researchers wrote. "In conclusion, in a free-viewing task, dogs seem to target their fixations at naturally salient and familiar items."

The findings are yet another reminder that man's best friend is smarter than some might give them credit for. And although it's a pleasant reminder, Vainio's study is not the first to explore facial recognition in dogs. A 2010 study looked into real-life recognition, and consisted of two experiments. The first experiment involved two people — the dog's owner and a stranger — walking back and forth in a room, and crossing each other's paths, as the dog watched. Naturally, the dog was more interested in watching its owner. When the two people left the room, the researchers watched as the dogs walked toward the door that the owner left from. The second experiment was the same as the first, however, both participants had bags over their head, effectively hiding their identity from the dogs - they were much less attentive to their owners. This suggested, the researchers said, that the dogs relied on facial recognition.

"If you imagine a dog in a real setting in a city, or anywhere in the middle of a crowd or a crowded space, you can see how the animal has adapted to give preferential attention to its owner," said Dr. Paolo Mongillo, of the University of Padua in Italy, according to BBC. "This is very likely to be a by-product of thousands of years of domestication."